1. Field of the Invention
This invention relates to toothbrushes for use in maintaining oral hygiene.
2. Description of the Prior Art
There is a build up of stains, plaque, calculous and other local irritants on the lingual aspects 19 (FIG. 1) of Anterior teeth (i.e., the premolars 16a, 16b, cuspids 17, and incisors 18a, 18b), even in dentists and very hygienic patients. These local irritants are a known factor in the etiology of periodontal disease. Peridontal disease is one of the leading causes of tooth loss in adults. There is a build up of such local irritants on the lingual aspects of anterior teeth because they are not very efficiently removed even with careful and frequent use of a standard toothbrush of the prior art and the generally recommended "Modified Bass" toothbrushing technique for removing these irritants. In utilizing the Modified Bass technique, as shown in FIG. 2, the bristles 21 of the toothbrush 20 are held at approximately 45.degree. to the surface of the teeth 22, and the brush is first moved slightly in a direction perpendicular to the length of the teeth (i.e., parallel to the gums 23) in order to loosen particles from the teeth. The brush is then moved along the length of the teeth away from the gums, in order to remove loosened particles from the teeth. This works well in cleaning the facial portions of the teeth, but this method is extremely difficult, if not impossible, to perform on the lingual aspects 15 of the anterior teeth 16, and the distal aspects of the most distal tooth, such as the distal aspect 14 of molar 15a (FIG. 1). For this reason, the Modified Bass technique states that, to clean the linqual aspect of the anterior teeth, the toothbrush is held, as shown in FIG. 3, approximately parallel to the lingual aspect of the teeth with the bristles engaging the tooth at an angle of approximately 90.degree.. The modified technique makes no provision for cleaning the distal aspect of the most distal teeth, because the toothbrushes of the prior art are not suitable for cleaning the distal aspect of the most distal teeth.
The Modified Bass technique is not very efficient in cleansing the lingual aspects of anterior teeth and the distal aspect of the most distal teeth for at least two reasons. First, the shape of prior art toothbrushes is such that the bristles do not get down into the sucular areas 25 (FIG. 1). Utilizing a standard prior art toothbrush and the Modified Bass technique, the bristles 27 also impinge on the gingiva 26a (the portion of gums 26 nearest the crown 29 of the teeth). Because of the high sensitivity of gingiva 26a, it is very difficult for the patient to cleanse the sulcular area 25 without causing damage to the gingiva 26a. Secondly, it is extremely difficult to maneuver a standard prior art toothbrush as required by the Modified Bass technique in the lingual areas 19 of anterior teeth.
The so-called "REACH" toothbrush currently being marketed includes a head for containing bristles, the head being bent slightly from the handle. The REACH toothbrush also has shorter bristles toward the outer and longer bristles at the sides of the head, in an attempt to enhance sulcular cleansing when the toothbrush is held such that the bristles are parallel to the occlusal plane. This structure allows slightly improved access to the distal areas and lingual aspect of anterior teeth, but still not a significant improvement over the prior art toothbrushes.
Other prior art toothbrushes, other than prior art toothbrush 28 of FIG. 3, are generally designed to brush the three accessable surfaces of teeth simultaneously. These three accessable surfaces of the teeth are shown in FIG. 4, and comprise the facial surface 30, the occlusal surface 31, and the lingual surface 32. Such prior art brushes generally consist of either a horseshoe shaped head having bristles of even length, such as described in U.S. Pat. No. 864,054 or having bristles of various lengths, as shown in U.S. Pat. No. 1,133,930. U.S. Pat. No. 1,133,930 includes longer bristles for brushing the facial and lingual aspects of the teeth, and shorter bristles for brushing the occlusal surface of the teeth. Other prior art toothbrushes, such as described in U.S. Pat. No. 1,353,780 have multiple heads. These toothbrushes typically include two or three heads having a variety of angles and lengths, but their main function is to brush several accessable surfaces or all of the teeth simultaneously. Other prior art toothbrushes are designed to attempt to brush both the upper and the lower teeth, and still other prior art toothbrushes have a rotary head. However, the objective in such prior art toothbrushes is to clean the accessable surfaces of the teeth simultaneously. In spite of the number of attempts to design better toothbrushes, proper cleansing of the lingual aspects of the anterior teeth and the distal aspect of the most distal teeth remains elusive, with no prior art toothbrush providing a satisfactory cleansing of these troublesome areas of the teeth.